Memory devices that use magnetism, such as a hard disk drive (HDD) and a magnetoresistive random access memory, have been developed. In order to increase the storage density of the memory, magnetic bodies used in the memory devices have been miniaturized. Due to the miniaturization of the magnetic bodies, a magnetic field used for the operation of the memory needs to be applied to the micro magnetic body. However, as the magnetic field has the property of spreading in space, it is difficult to locally generate the magnetic field. If a magnetic field generating source is reduced in size to form a local magnetic field, it may be impossible to form a sufficient size of a magnetic field to control the magnetization direction of the magnetic body.
One technique is known to solve this problem in the MRAM. “Spin transfer switching” that passes a current through a magnetic body to switch the magnetization direction of the magnetic body is studied as one method of writing data in the MRAM. According to this spin transfer switching, a write current is passed through a magnetoresistive effect element, and spin-polarized electrons generated therein are used to switch the magnetization direction of a magnetic body (magnetic layer) in the magnetoresistive effect element.
The use of this spin transfer switching allows a magnetization condition in a nano-scale magnetic body to be easily controlled by the local magnetic field and also allows the value of the current for switching the magnetization to be reduced in accordance with the magnetization of the magnetic bodies.
Recently, studies have been carried out to use, for a reference layer and a storage layer of the magnetoresistive effect element of the MRAM, a perpendicular magnetization film having its magnetization direction in a direction perpendicular to a film plane.